Indoor and Outdoor Air Contaminant Exposures. Asthma is the most common chronic disease of childhood in the developed world, affecting about 10 million U.S. children under the age of 16. Asthma is particularly prevalent among urban populations and minority populations. The causes of these increases and the differential risk for urban, minority populations are not well understood. The national trends in the increase in asthma are visible in Detroit. The causation, and aggravation, of pediatric asthma is complex and multi-factorial and includes genetic disposition, demographic variables, psychosocial stressors, and environmental exposures. Environmental exposures include both ambient outdoor exposures as well as indoor exposures within the home and at school. Understanding the importance of the various environmental co-factors is complicated by the dynamic nature of ambient pollutants and the varying exposures that result. The first specific aim will determine the prevalence of questionnaire defined asthma among the elementary age schoolchildren in two distinct minority urban populations in Detroit. Students and their families from 10 to 12 elementary schools (approximately 6000 students) in two areas in which the investigators have pre-existing strong community times, i.e., southwest Detroit ('southwest') and the east side of Detroit ('eastside'), will be solicited to complete a short, well validated asthma screening questionnaire. The second specific aim will investigate which components of the ambient air, or indoor air contaminants, and family and neighborhood characteristics are associated with increased risk for asthma in this population. The third specific aim will investigate whether seasonal and daily fluctuations in ambient air pollution and indoor air contaminants are predictive of fluctuations in asthma disease status. The last specific aim will provide ambient (community/neighborhood level), micro-environmental (schools and homes), and personal monitoring data to investigate the relationships between various exposure metrics and activity patterns of asthmatic children living in a large urban community.